Original Message:
Sent: 06-04-2025 21:10
From: Tim Foster
Subject: Action spread in a hurry
Thank you, everyone, for your help! I saw the piano from the OP today. I slightly moved the wippen rail forward, (very) rough regulated it, including fixing excessive aftertouch (some sections 90 thousandths!). A few other odds and ends repairs. Happy customer and I think it will be a much safer piano to play moving forward, even though the regulation was rough.
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Tim Foster RPT
New Oxford PA
(470) 231-6074
Original Message:
Sent: 05-22-2025 08:42
From: Peter Grey
Subject: Action spread in a hurry
Quick and dirty: Look at the profile of the jacks relative to the shank/knuckle. It SHOULD be a perfect right angle. If not, you know you have problems. 112mm - 113mm is considered basic accurate action spread for a well designed action (recent journal article source).
Jacks breaking means there's TOO MUCH of something. Proper jack position at full dip should be halfway between knuckle and cushion in the window. If aftertouch is excessive you can 1) increase hammer blow (if available), 2) reduce key dip, 3) reduce let off (if excessive), 4) check keyframe bedding as studs may have been turned down excessively prior to you to achieve more afterthought leading to this problem (refer to 2 above)
If your spread is in the ballpark you must deal with one or more of these things. If not in the ball park, adjust and then observe.
Is this person a HEAVY player? I'm guessing yes...
Edit: Contrary to popular opinion, pianos are not DESIGNED to endure heavy use. Anyone giving heavy use must be sternly warned that they need much more maintenance than with moderate use. That means money...
Peter Grey Piano Doctor
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Peter Grey
Stratham NH
(603) 686-2395
pianodoctor57@gmail.com
Original Message:
Sent: 05-21-2025 09:32
From: Floyd Gadd
Subject: Action spread in a hurry
I guess I might also say that if excessive action spread is the real problem, it may be impossible to achieve even a minimally adequate amount of aftertouch. One way of looking at changing action spread is seeing it as changing the location of the jack window in the repetition lever, in relation to the knuckle. Reducing action spread means moving the jack window closer to the hammer action flange, providing more wiggle room for the jack once it clears the knuckle.
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Floyd Gadd RPT
Regina SK
(306) 502-9103
Original Message:
Sent: 05-21-2025 07:25
From: Floyd Gadd
Subject: Action spread in a hurry
Actually, dip is not the first thing I think of when it comes to changing aftertouch. Of course, if key dip is excessive or irregular (I tend toward 10.3mm or 13/32" as a norm, but 9.5mm or 3/8" is not ridiculously shallow) it will need to be dealt with, but working with the capstan at the back of the key is the main event. Excessive let-off leads to excessive jack excursion, so that needs to be right as well, but the key capstan/hammer blow adjustment is the focus of the negotiation. The right adjustment is not finally determined by some textbook value for hammer blow, but rather by what gives you the right amount of aftertouch.
Once correct aftertouch has been established for a few samples, it is time to press firmly on a key with the action in the piano, then tap on the toe of the jack to see if further movement is possible. If the jack has nowhere to go, then you're dealing with excessive action spread.
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Floyd Gadd RPT
Regina SK
(306) 502-9103
Original Message:
Sent: 05-21-2025 01:00
From: Steven Rosenthal
Subject: Action spread in a hurry
I'm curious about where the jacks are breaking. If it's right at the jack regulating screw, it could be that the holes were drilled too small. That was the case of the only time I've run into multiple jacks breaking; this was on a Kawai grand with ABS jacks and they'd had that problem at some point with some pianos. Ultimately I had to replace the whole set of jacks. Hole too small or a batch of regulating screws a little big, maybe plated twice or something.
If the client doesn't want to give you the time or spend the money to fix the issue, that is her problem, not yours. As a stop-gap to get her through the week you might get away with adjusting to give minimal let off. It will reduce power but might save the jacks. And/or like Floyd says, reduce the dip/aftertouch.
Other's can speak better to geometry issues than I can.
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Steven Rosenthal RPT
Honolulu HI
(808) 521-7129
Original Message:
Sent: 05-20-2025 21:31
From: Floyd Gadd
Subject: Action spread in a hurry
Did you eliminate the possibility of excessive aftertouch before moving forward with the assumption that action spread was the issue? I usually aim for .045" of aftertouch (1.1mm) but in consultation with the Fazioli factory head technician went with .031" (.8mm) to resolve a regulation puzzle in our university's F278. That spec still yielded a very satisfying experience for the high profile artist for whose performance the piano was being made ready.
Limiting aftertouch may not take you far enough to eliminate the jamming of the jack, but if it does, you have found a way to reach your goal while at the same time limiting the instrument's down-time, which seems to be a high priority for your client.
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Floyd Gadd RPT
Regina SK
(306) 502-9103
Original Message:
Sent: 05-20-2025 20:25
From: Wim Blees
Subject: Action spread in a hurry
The action spread might be what it's supposed to be, but I would look at the jack placement under the knuckle. It's one of the most overlooked specs when regulating an action. If all of them are too far forward, moving the wippen rail backwards will solve the action spread at the same time. Not having the wippen rail tightened down will also solve the "Whac-A-Mole" problem.
Original Message:
Sent: 5/20/2025 7:20:00 PM
From: Tim Foster
Subject: Action spread in a hurry
Hello, I have scheduled an appointment early next month to deal with a problem that a local piano teacher is having with her (Chinese) Hamilton tiny grand. She calls them sticking keys, but they are broken jacks that are smashing into the window and breaking on a hard blow, the hammer then pinning against the strings. I confirmed this last time when there wasn't time to correct the problem and she has hesitated to schedule time to fix, until now. I'm going to repair what's broken and try to correct the action spread, which I suspect is the issue. The problem is she wants to be able to use the piano in the afternoon, and I really don't think extensive work/regulation is in her budget. I haven't had to correct action spread yet, and I want to make sure I'm thinking through it reasonably before then. What regulation procedures would you prioritize to get things in the ballpark after changing action spread? Anything else that should be in my radar? I've seen this piano a couple times and it's like playing Whac-A-Mole, repairing loose centers, etc.
Thank you!
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Tim Foster RPT
New Oxford PA
(470) 231-6074
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